The mechanism responsible for retrieval-induced forgetting has been the subject of rigorous theoretical debate, with some researchers postulating that retrieval-induced forgetting can be explained by interference (J. G .W. Raaijmakers & E. Jakab, 2013) or context reinstatement (T. R. Jonker, P. Seli, & C. M. MacLeod, 2013), whereas others claim that retrieval-induced forgetting is better explained by inhibition (M. C. Anderson, 2003). A fundamental assumption of the inhibition account is that nonpracticed items are suppressed because they compete for retrieval during initial testing. In the current study, we manipulated competition in a novel interpolated testing paradigm by having subjects learn the nonpracticed items either before (high-competition condition) or after (low-competition condition) they practiced retrieval of the target items. We found retrieval-induced forgetting for the nonpracticed competitors only when they were studied before retrieval practice. This result provides support for a critical assumption of the inhibition account.